Following the development of electronic industries, the performances of all kinds of electronic components have been rapidly promoted to have faster and faster processing speed. Also, an electronic component contains more and more chips therein. The chips work at high speed and generate high heat at the same time. The heat must be efficiently dissipated outward. Otherwise, the performances of the electronic component will be greatly affected to slow down the operation speed of the electronic component. In some serious cases, the electronic component may be burnt out due to overheating. Therefore, heat dissipation has become a critical topic for all kinds of electronic components. A cooling fan is often used as a heat dissipation device for electronic components.
The conventional cooling fans can be divided into plastic-made fans and metal-made fans. In practice, the plastic-made cooling fans have lower durability than the metal-made cooling fans. For example, the blades of a plastic fan are subject to damage due to collision or compression. Therefore, metal cooling fans have been more and more widely developed by manufacturers.
FIGS. 1A and 1B are perspective exploded and perspective assembled views of a conventional metal-made cooling fan. The cooling fan includes a hub 10 and a blade assembly 12 having multiple blades 121 and a connection member 122. The blades 121 extend from a circumference of the connection member 122 to form the blade assembly 12. The blade assembly 12 is capped on the hub 10 with the connection member 122 and the blades 121 attaching to the top face and outer circumference of the hub 10 respectively. The blades 121 and the connection member 122 are fixedly point-welded on the top face and the outer circumference of the hub 10 respectively to form the cooling fan.
The above metal-made cooling fan is free from the problem of poor durability and is not so easy to damage as the plastic cooling fan. However, the metal-made cooling fan has otherwise problems. The blade assembly 12 is made with a press mold (not shown). The connection member 122 is first made by means of pressing. Then the blades 121 are continuously formed by means of pressing. When pressing the blade assembly 12, intervals must be reserved between the blades 121 for pressing the blades 121. Due to the reserved intervals, it is impossible to press the blades in an overlapping pattern. As a result, the wind power of the cooling fan is unsatisfying. Moreover, the pressing process of the blade assembly 12 is complicated so that it is difficult to form the blade assembly 12 with the press mold. In comparison with a common mold for pressing one single blade at a time, the cost for the press mold is much higher.
Also, when assembling the blade assembly 12 with the hub 10, the blade assembly 12 is capped onto the hub 10 with the connection member 122 and the blades 121 attaching to the top face and the outer circumference of the hub 10 respectively. Thereafter, the blades 121 and the connection member 122 are point-welded on the top face and the outer circumference of the hub 10. However, when point-welded, the blade assembly 12 is simply attached to the hub 10 without being located thereon. Therefore, during the point-welding process, the blade assembly 12 and the hub 10 tend to displace from each other. As a result, the blades 121 can hardly be fixed in their true positions. In this case, the blades 121 will produce turbulent airflow to cause wind resistance. Consequently, the wind power of the cooling fan will be deteriorated.
According to the aforesaid, the conventional cooling fan has the following shortcomings:
1. The manufacturing cost for the conventional cooling fan is high.
2. The wind power of the conventional cooling fan is low.
3. It is hard to manufacture the conventional cooling fan.